Once it enters your mouth, it is in there and you can't get rid of it and the body has to do something with it.

一旦它进到你嘴里，它就在那里，你不能消除它，身体必须对它做些什么。

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In addition, you may catch flu when touching something with flu viruses on it and then touch your mouth, eyes, or nose.

此外，接触上头有流感病毒的物品后，再触摸自己的嘴巴、眼睛或鼻子等，你便可能因此染上流感。

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"When you're greeted with something that's less than welcoming, that first taste in your mouth is quite disconcerting, " said Geoff Freeman, chief operating officer of the U.S. Travel Association, the industry trade group that conducted the survey in partnership with Consensus Research.

CNN: Survey: U.S. Customs is driving visitors away